If it feels like there are a lot more commercials on network TV these days, it’s not just because you’ve become accustomed to ad-free Netflix. A thread on AVS Forum from 2013 found that TBS sped up episodes of Seinfeld by 7.5 percent to air more ads. The clip that shows a side-by-side comparison of the TBS episode and the original episode has been removed because of a copyright infringement, but there’s an updated YouTube video from 2015 that shows a Seinfeld episode being sped up by 9 percent:

One drive behind this is falling television ratings, which lowers the cost of individual commercial slots. To compensate for lost revenue, TV companies are airing more ads. In response to the increasing number of commercials, television shows have gotten shorter—The Big Bang Theory episodes have an average runtime of 22 minutes, compared to I Love Lucy episodes, which average 30 minutes. Older shows on television are often edited or slightly sped up to make more room for commercial breaks. Cable networks have also shortened opening credits for TV shows to increase ad time.

However, this technique may be changing as television ratings fall even farther as competitors like Netflix and Hulu take over the TV market. According to an article in The New York Times from 2016, big broadcasting companies like Turner and Viacom (which owns MTV, Comedy Central, and Nickelodeon) have begun to cut back on commercials and shift their focus to programming sponsored by brands, like when NBC teamed up with American Express on Leap Day to create extended segments of popular NBC shows.